高温高产井井口抬升及下沉风险分析研究

Risk Analysis of Wellhead Uplift and Subsidence in High Temperature and High Yield Wells

由高温热膨胀效应引发的井口抬升现象在各大油田普遍存在,严重威胁生产作业安全。基于多级传热理论,通过有限元方法模拟多级套管水泥环地层非线性传热过程及热膨胀现象,提出了一种新的井口抬升计算方法。以新疆油田某区块X1井为例,开展了不同工况下各级管柱井口风险评价分析。研究发现,在极限生产工况下,由于表层套管环空水泥环产生的封固作用,使得各级套管在井口位置处虽产生较大上顶力,但并不会发生井口抬升现象;而当表层套管水泥环存在一定程度缺失后,井口出现整体抬升现象,且在井口装置压重作用下,井口整体抬升量从0.03 m缩减至0.02 m。结果表明,该方法可以定量评价实际生产过程中井口安全性,对实际现场井口抬升计算及风险评价具有一定指导意义。

The phenomenon of wellhead growth caused by high temperature thermal expansion is widespread in major oil fields,which seriously threatens production safety.Based on the multistage heat transfer theory,the nonlinear heat transfer process and thermal expansion phenomenon of multistage casing-cement sheath-formation are simulated by finite element method,and a new wellhead lift calculation method is proposed.Taking Well X1 of a block in Xinjiang Oilfield as an example,the risk assessment and analysis of various string wellhead under different working conditions are carried out.It is found that under the limit production conditions,although the casing at all levels has a large lifting force at the wellhead due to the cementing effect of the casing annulus,the wellhead uplift phenomenon does not occur.However,when the casing cement sheath is damaged to a certain extent,the overall wellhead lift occurs,and the overall wellhead lift decreases from 3 cm to 2 cm under the action of the pressure and weight of the wellhead device.The results show that this method can quantitatively evaluate the wellhead safety in the actual production process,and has certain guiding significance for the actual field wellhead lifting calculation and risk evaluation.